On the back of the board is a STM32F4 and a microSD card slot ... through a standalone mode with pins connected to a button or sensor, to the SPI bus on a microcontroller, or a serial to Bluetooth ...

with the data pins filling in the obvious role. The code that actually drives the LEDs all happens on an STM32F4 with the help of DMA and FSMC, or the Flexible Static Memory Controller found on ...